This study is designed to define chromosome abnormalities which occur in acute non-lymphocytic leukemia. Chromosome abnormalities will be determined utilizing multiple banding techniques on metaphase chromsomes. Investigations into the possible application of prophasic banding techniques to acute leukemia cells will be carried out. The acute leukemias will be defined by morphological, cytochemical, and ultrastructural techniques which should allow for precise definition of sub-types. Correlations will be made between karyotypic abnormalities and specific sub-types of acute leukemia. Chromosome abnormalities as prognostic indicators will continue to be evaluated.